1. Field of Industrial Utilization
This invention relates to a vacuum pump and, more particularly, to a vacuum pump which is suitable for preventing adhesion of reaction products by a process gas.
2. Prior art
Various vacuum pumps have recently been proposed in order to generate clean vacuum in apparatus for producing semiconductors. An example of such vacuum pumps is disclosed in, for example U.S. Pat. No. 4,668,160 wherein a gas sucked from a suction port is generally compressed sequentially while it passes through a flow path defined by a rotor and a stator and the compressed gas is discharged into the atmosphere.
In the vacuum pumps of this kind, materials in process gases handled in a semiconductor production apparatus which are likely to be solidified adhere and are deposited in the flow path and in order to remove such deposits easily, some vacuum pumps have a structure which can be disassembled and assembled easily, as disclosed in, for example, Japanese Utility Model Laid-Open No. 43197/1985.
In accordance with the prior art described above, the gas flow path is closed when the reaction products adhere or are deposited on the flow path of the process gas, so that the pump is disassembled in order to remove the deposits. Therefore, the operation of the semiconductor production apparatus connected to the vacuum pump must be stopped and the work efficiency is reduced.